Abstract: This work was devoted to investigate the gamma transient ionizing radiation effect of two kinds of BiMOS op-amp (JFET-Bi, PMOS-Bi). The experimental results indicate the changing of the disturbance duration of the BiMOS op-amp output with dose rate shows some regularity. The time of the transient radiation disturbance increases exponentially with dose rate while the dose rate is low, and the disturbance duration presents saturated characteristics while in high dose rate. What’s more, the disturbance duration of the output also behaves some differences for different input signals.